package com.example.demo.common;

import java.util.List;

public class PageUtils {

	/**
     * 开始分页
     *
     * @param list
     * @param pageNum  页码
     * @param pageSize 每页多少条数据
     * @return
     */
    public static List startPage(@SuppressWarnings("rawtypes") List list, Integer pageNum, Integer pageSize) {
        if(list == null){
            return null;
        }
        if(list.size() == 0){
            return null;
        }
 
        Integer count = list.size(); //记录总数
        Integer pageCount = 0; //页数
        if (count % pageSize == 0) {
            pageCount = count / pageSize;
        } else {
            pageCount = count / pageSize + 1;
        }
 
        int fromIndex = 0; //开始索引
        int toIndex = 0; //结束索引
 
        if (pageNum != pageCount) {
            fromIndex = (pageNum - 1) * pageSize;
            toIndex = fromIndex + pageSize;
        } else {
            fromIndex = (pageNum - 1) * pageSize;
            toIndex = count;
        }
 
        List pageList = list.subList(fromIndex, toIndex);
 
        return pageList;
    }

 
	
}
